This contract is for a clinical center which is one of an estimated twenty five centers that will conduct a large scale clinical trial on left ventricular dysfunction. The primary objective of the trial is to answer two questions: (1) In patients with moderate left ventricular dysfunction and little or no overt heart failure, can death be prevented? (2) Is mortality reduced by treatment in those with manifest heart failure? Two concurrent but distinct randomized double blind controlled trials will be conducted. The first will be the Prevention Trial and will be placebo controlled. The second will be the Treatment Trial and patients will be randomized to "standard" treatment + placebo or "standard" treatment + active agent. The Prevention Trial has an anticipated enrollment of at least 4,000 patients and the Treatment Trial of at least 2,000 patients.